Device for connecting structural components

ABSTRACT

A device for connecting two structural components, comprising:  
     a base part disposed at one structural component,  
     a spacer having a threaded portion in threaded engagement with the base part, said spacer being supported with one end thereof at the other structural component,  
     a connecting screw inserted frictionally engaged through the spacer,  
     a shoulder formed at one end of said threaded portion of the spacer, and  
     an abutment to be engaged by said shoulder and being formed at the base part,  
     wherein said abutment is arranged to become effective to limit, through engagement with said shoulder, a threading movement of the spacer in one direction relative to the base part only after the base part and the spacer have been assembled.

BACKGROUND OF THE INVENTION

[0001] The invention relates to a device for connecting structuralcomponents, comprising a base part attached to one of said components, aspacer which is in-threaded engagement with the base part and has an endsupported at the other structural component, and a connecting screwwhich is inserted frictionally engaged through the spacer.

[0002] A known device of this type is described in U.S. Pat. No.4,682,906 and is used to connect two structural components, which aredisposed at a particular distance from one another, with the help of theconnecting screw, without distorting the structural components as theconnecting screw is tightened. The connecting screw is inserted, forexample, through the structural component, which is to be supported atthe spacer, and is then screwed into an internal thread of the otherstructural component which is connected with the base part. During thisscrewing-in motion, the spacer is taken along by friction. The threadbetween the spacer and the base part is a left-handed thread, so thatthe spacer is screwed further out of the base part and approaches thestructural component, which is held by the head of the connecting screw,until this component finally lies in contact with the front surface ofthe spacer.

[0003] However, if the distance between the structural components whichare to be connected is greater than the maximum adjusting path of thespacer, it may happen that, as the connecting screw is screwed in, thespacer is screwed completely out of the base part. Since the spacer inthis case is accessible only with difficulty, if at all, it is difficultto restore the threaded engagement between the spacer and the base part.

[0004] In the state of the connecting device as delivered, the spacernormally is screwed completely into the base part. From practice, aconnecting device is known, in which the spacer in this position is incontact with a stop and, in addition is held in position by a resilienttab. It must however be possible to overcome the resistance of this tabwhen the connecting screw is screwed in. Accordingly, it cannot beexcluded that, because of improper handling or jarring, the spacer,before use of the connecting device, becomes detached completely fromthe base part, so that the parts of the connecting device fall apart andare lost. Another embodiment of a connecting device of this type isdisclosed in applicant's co-pending U.S. patent application Ser. No.09/920,201.

SUMMARY OF THE INVENTION

[0005] It is an object of the invention to provide a device of the typeindicated above, in which the spacer and the base part are held togetherso as to be prevented from getting lost.

[0006] According to the invention, this object is achieved by the factthat the movement of the spacer relative to the base part in onedirection is limited by a shoulder that is formed at an end of thethreaded portion of the spacer and engages an abutment at the base part,which abutment becomes effective only after the spacer and the base parthave been assembled.

[0007] Thus, in the device according to the invention, it is possiblethat the spacer is initially screwed into the base part and then theabutment is made effective, so that the spacer can no longer be screwedout of the base part completely. If necessary, the movement of thespacer relative to the base part in the other direction may be limitedby normal stops, so that it is not possible, neither, to screw thespacer completely through the base part. In this way, the spacer and thebase part, once assembled, are held together so that the may not getlost.

[0008] In one embodiment, the abutment, which becomes effective onlyafter assembly, is formed by a spring member which projects radiallyinward from the base part, for example a spring member in the form of aresilient tab which retreats, when the spacer is screwed in, and whichthen locks behind the shoulder of the spacer.

[0009] In another embodiment, the abutment is rigidly provided on ajacket into which a threaded sleeve is press-fitted. In this embodiment,the spacer is at first screwed into the threaded sleeve, and only thenis the threaded sleeve pressed into the jacket of the base part, so thatthe abutment is made effective.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the following, embodiment examples of the invention areexplained in conjunction with the drawings, in which:

[0011]FIG. 1 shows an axial section through a connecting device and twostructural components to be connected,

[0012]FIG. 2 shows a connecting device according to another embodiment,and

[0013]FIG. 3 shows a part of the connecting device of FIG. 2 in a frontview.

DETAILED DESCRIPTION

[0014] In FIG. 1, two plate-like structural components 10, 12 are shown,which are to be connected to one another at a distance from one anotherby a connecting device 14. The connecting device 14 is formed by a basepart 16 which is held at the structural component 10, a spacer 18 thatis screwed into the base part 16, and a connecting screw 20 which isinserted through the structural component 12 and into a central bore ofthe spacer 18 and, during the establishment of the connection, isscrewed into a threaded bore 22 of the structural component 10.

[0015] The base part 16 has a threaded metal sleeve 24 which issupported at the component part 10 and has a knurled outer peripheryonto which a plastic jacket 26 is pressed. The jacket 26 forms two claws28 with which the base part 16 is non-rotationally clipped to thecomponent part 10.

[0016] The spacer 18 is made of metal in its entirety. The threadedsleeve 24 of the base part and the spacer 18 are in threaded engagementwith one another through a left-handed thread 30. A spring collar 32 ispressed into a central bore of the spacer 18 and is in frictionalengagement with the external thread of the connecting screw 20.

[0017] When the connecting screw 20 is screwed into the threaded bore 22of the component part 10, the spacer 18 is rotationally entrained,whereas the base part 16 is held non-rotatable by the claws 28. Becauseof the left-handed thread, the spacer 18 is therefore screwed out of thebase part 16, so that it approaches the component part 12 which in turnis pressed against the spacer by the head of the connecting screw 20.

[0018] The left-handed thread 30 of the spacer 18 is limited at one endthereof, on the right side in FIG. 1, by a shoulder 34. The innerperipheral surface of the jacket 26 is formed with an annular collar 36at which one end of the threaded sleeve 24 is supported. A resilient tab38 projects inwardly from the collar 36 at at least one location of theperiphery of the latter. This tab 38 forms an abutment which cooperateswith the shoulder 34 and thereby limits the maximum expansion stroke ofthe spacer 18.

[0019] The spacer 18 has, at its end facing the component part 12, aradially projecting flange 40 which provides an engagement surface forthe component part 12 when the component parts 10 and 12 are clampedtogether by the connecting screw 20. In the condition shown in FIG. 1,in which the spacer 18 is still completely accommodated within the basepart 16, the outer end face of the flange 40 is flush with the end faceof the base part 16. A projection 42 which radially projects from theedge of the flange 40 engages an inwardly projecting stop 44 of the basepart. The stop 44 thus prevents the spacer 18 from being rotated in thecounterclock sense, as seen in the direction in which the connectingscrew 20 is screwed in. Consequently, the spacer 18 cannot be displacedtowards the component part 10 beyond the position shown in FIG. 1. When,however, the connecting screw 20 is screwed in clockwise direction intothe threaded sleeve 24, the spacer 18 can co-rotate in the clock sense,because the projection 42 is then lifted from the stop 44. After onecomplete turn of the spacer 18, the projection 32 has moved already outof the base part 16 to such an extent that it can now move past the stop44 of the base part.

[0020] It is thus assured in the shown embodiment that the spacer 18cannot be screwed out of and removed from the base part 16, neither inthe one direction nor in the other.

[0021] When the connecting device is being assembled, the spacer 18 canhowever be screwed into the threaded sleeve 24 of the base part from theright end in FIG. 1. Then, the elastic tab 38 is at first bent inwardly,so that it retreats from the spacer 18. When the spacer is screwed-infurther, the tab 38 slips over the external thread of the spacer, and itfinally slips over the shoulder 34, so that it returns elastically intoits original position in which it acts as an abutment for the shoulder34.

[0022]FIGS. 2 and 3 show, as another example, a connecting device 46 inwhich the connecting screw 20 is screwed-in from the opposite end. Inthis case, the component part 10 has an opening 48 shaped like a keyhole and having two diametrically opposed extensions 50 for receivingthe claws 28. The circular inner part of the opening 48 is covered by adisk 52 at which the head of the connecting screw 20 and the threadedsleeve 24 of the base part 16 are supported.

[0023] The threaded sleeve 24 and the spacer 18 have in this caseright-handed threads, so that the spacer 18 is extended towards thecomponent part 12, to the right in FIG. 2, when the connecting screw 20is turned clockwise.

[0024]FIG. 2 shows the spacer 18 already in the extended condition, inwhich the shoulder 34 has almost reached the abutment position. However,the abutment at the jacket 26 is in this case not formed by a resilienttab but by a rigid projection 54. The flange 40, which is formed at thespacer 18 and which, in this case, has a smaller diameter, has, at onelocation of its periphery, a recess 56 through which the projection 54may pass in axial direction.

[0025] When the connecting device 46 is assembled, the threaded sleeve24 and the spacer are first screwed together, before the threaded sleeve24 is pressed into the jacket 26. As a result, the spacer 18 can bescrewed into the threaded sleeve 24 from the right side in FIG. 2, untilit has approximately reached the screwed-in position shown in FIG. 2.Then, the spacer 18 and the threaded sleeve 24 are, together, insertedinto the jacket 26 from the left side in FIG. 2. At this instant, thespacer 18 is held in an angular position in which the projection 54 canpass through the recess 56. In a final phase of the insertion movement,the threaded sleeve 24 is then pressed into the jacket 26 with itsknurled outer periphery. Finally, the spacer 18 is screwed deeper intothe threaded sleeve 24, until its opposite end faces are flush with thecorresponding end faces of the base part 16. In this condition, in whichthe connecting device has its smallest possible axial dimension, thebase part 16 is then clipped to the component part 10, and theconnecting screw 20 is inserted and screwed-in, so that the spacer 18 isextended again.

[0026]FIG. 3 shows a part of the end face of the flange 40 as well as apart of a boss 58 which is formed at the jacket 26 and surrounds theflange 40. In the condition shown in FIG. 3, the recess 56 formed in theperiphery of the flange 40 is angularly displaced from the projection 54of the base part. Adjacent to the left flank, as seen in FIG. 3, of therecess 56, there is formed a projection 60 which projects radiallyoutwardly from the edge of the flange 40. An inwardly projecting stop 62and a bridge-shaped retaining spring 64 are molded to the internalperipheral surface of the boss 58. As long as the flange 40 is in anaxial position outside of the base part, as in FIG. 2, the spacer 18 canbe rotated clockwise and hence be screwed deeper into the base part 16.During the last turn, immediately before the smallest axial dimension isreached, the flange 40 enters into the boss 58. The projection 60 slipsat first over the retaining spring 64, while overcoming a certainretaining resistance, and then abuts at the stop 62. In this way, thespacer 18 is prevented from being screwed-in further. The retainingspring 64 retains the spacer in the then-reached position, whichcorresponds to the smallest axial dimension, and prevents the spacerfrom being misadjusted due to vibrations. However, the force of theretaining spring 64 is dimensioned such that it can be overcome by thefrictional coupling between the connecting screw 20 and the spacer, whenthe connecting screw 20 is screwed in. During this operation ofscrewing-in the connecting screw, the spacer 18 turns left in the viewshown in FIG. 3, so that the projection 60 moves away from the stop 62.

What is claimed is:
 1. A device for connecting two structuralcomponents, comprising: a base part disposed at one structuralcomponent, a spacer having a threaded portion in threaded engagementwith the base part, said spacer being supported with one end thereof atthe other structural component, a connecting screw inserted frictionallyengaged through the spacer, a shoulder formed at one end of saidthreaded portion of the spacer, and an abutment to be engaged by saidshoulder and being formed at the base part, wherein said abutment isarranged to become effective to limit, through engagement with saidshoulder, a threading movement of the spacer in one direction relativeto the base part only after the base part and the spacer have beenassembled.
 2. The device of claim 1, wherein said abutment is formed bya spring member, which retreats when the spacer is screwed into the basepart, and which then locks behind said shoulder.
 3. The device of claim2, wherein said base part has a threaded sleeve made of metal and ajacket of plastic, and said spring member is formed at said jacket. 4.The device of claim 1, wherein the base part comprises a threaded sleevemade of metal and a plastic jacket, the threaded sleeve is press-fittedin said jacket, and said abutment is formed rigidly at the jacket. 5.The device of claim 1, wherein the spacer has an end adjacent to saidshoulder and, at this end, a radially projecting flange and a projectionextending from said flange, and the base part has a stop defining an endposition for the spacer, and wherein, when the spacer reaches said endposition, the projection engages the stop and thereby limits a furtherrotary threading movement of the spacer relative to the base part. 6.The device of claim 2, wherein the spacer has an end adjacent to saidshoulder and, at this end, a radially projecting flange and a projectionextending from said flange, and the base part has a stop defining an endposition for the spacer, and wherein, when the spacer reaches said endposition, the projection engages the stop and thereby limits a furtherrotary threading movement of the spacer relative to the base part. 7.The device of claim 3, wherein the spacer has an end adjacent to saidshoulder and, at this end, a radially projecting flange and a projectionextending from said flange, and the base part has a stop defining an endposition for the spacer, and wherein, when the spacer reaches said endposition, the projection engages the stop and thereby limits a furtherrotary threading movement of the spacer relative to the base part. 8.The device of claim 4, wherein the spacer has an end adjacent to saidshoulder and, at this end, a radially projecting flange and a projectionextending from said flange, and the base part has a stop defining an endposition for the spacer, and wherein, when the spacer reaches said endposition, the projection engages the stop and thereby limits a furtherrotary threading movement of the spacer relative to the base part. 9.The device of claim 8, wherein a recess, which is complementary to saidabutment of the base part, is formed in an outer periphery of saidradially projecting flange.